JPH02114835A - Fuel pump motor - Google Patents

Abstract

PURPOSE:To obtain a fuel pump motor having excellent durability by forming a special composite galvanization layer on the contact face of a commutator with a brush thereby reducing corrosion and abrasion of the commutator and the brush. CONSTITUTION:A composite galvanization layer 1a composed of nickle, phosphorus and conductive micro hard particles, i.e., silicon carbide particles, is formed on the contact face of a commutator 1 with a brush 2. Nickle and phosphorus are contained in the galvanization layer 1a with weight ratio of 94:6-90:10. The thickness of the galvanization layer 1a is in the range of 1-200mum. Grain size of silicon carbide in the composite galvanization layer 1a is smaller than 5mum and the content thereof is in the range of 1.5-10wt.%. By such arrangement, the commutator can be protected against degradation due to corrosion or abrasion resulting in considerable improvement of durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel pump electric motor, and more particularly to a commutator thereof.

[Prior Art] Figure 3 is a partial cross-sectional view showing a commutator and brushes of an electric motor used in a conventional automobile fuel pump.
The commutator 1 and the brush 2 provided around the insulating member 4 formed around the shaft 3 are in contact with each other by known elastic means. This commutator 1 is usually made of copper-based metal, and rectifies current by coming into contact with rotating commutator pieces or brushes 2.

[Problems to be Solved by the Invention] However, when the above-mentioned electric motor is used in a liquid fuel such as gasoline, the metal such as copper that constitutes the commutator 1 may react with the sulfur or chlorine in the gasoline. This generates sulfides and chlorides, which increase the contact resistance between the commutator 1 and the brushes 2, resulting in insufficient rectification and impeding pump operation.

Furthermore, the commutator 1 is subjected to a corrosive action due to the moisture present in the carbon, forming a film of hydroxide or oxide on its surface. Therefore, the contact resistance between the commutator 1 and the brush 2 increases, which affects the performance of the pump.

In addition, the fuel pump may be equipped with a filter to remove solid foreign matter from the fuel, or fine particles with large hardness that pass through this filter may enter between the commutator l and the brush 2, causing the soft brush 2 to hammered into the surface. As a result, the wear of the commutator 1 in contact with the brush 2 is accelerated, and the durability of the electric motor is impaired. In addition, the worn metal powder on the commutator 1 causes the fuel to become rancid, and the rancid fuel is further
There is a problem that it corrodes the surface and increases wear.

Further, if the fine particles implanted into the brush 2 are conductive substances, an arc is generated between the brush 2 and the commutator 1, which has a rough surface due to wear, promoting electrical wear of the commutator 1.

Furthermore, various additives to improve combustion characteristics and detergents to keep the engine clean are added to Kallin. Therefore, there is almost no carbon adhesion from the brush 2 to the contact surface of the commutator 1 with the brush 2, and not only the friction reduction effect of the brush 2 is not performed, but also a hard oxide film is formed on the surface of the commutator 1. Since it becomes difficult to form, wear of the commutator 1 is further accelerated.

This invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel pump electric motor that reduces corrosion and wear of the commutator and brushes and has excellent durability.

[Means for Solving Problem 1] The fuel pump electric motor of the present invention includes nickel and phosphorus in a weight ratio of 90:10 to 94:6 and a particle size of 5 μm or less on the contact surface of the commutator with the brush. A composite plating layer containing 1.5 to 10% by weight of conductive hard particles and having a thickness of 1 to 200 μm is formed.

[Function] In the fuel pump electric motor of the present invention, the composite plating layer formed on the contact surface of the commutator and brushes prevents corrosion of the commutator and brushes and suppresses an increase in contact resistance. A composite plating layer with desirable hardness and lubricity provided by fine particles prevents commutator wear.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the commutator 1 is provided around an insulating member 4 formed around a shaft 3, and is in contact with a brush 2. A composite plating layer 1a consisting of nickel, phosphorus, and silicon carbide powder as conductive hard particles is formed on the contact surface of the commutator 1 with the brush 2 by the known Kanigen method. It is desirable that the ratio is 94:6 to 90+10. This is because, beyond this range, nickel and phosphorus do not form intermetallic compounds, and wear resistance etc. are not necessarily sufficient. In addition, from the standpoint of promoting the formation of intermetallic compounds of nickel and phosphorus and improving wear resistance, it is desirable to heat-treat the plating layer at a temperature of 200°C or higher after plating, or even if no heat treatment is performed, this invention The basic effect of is achieved. The thickness of the plating layer 1a of this commutator 1 is preferably 1 to 200 μm. This is because if the thickness is less than 1 .mu.m, the underlayer is likely to become hazy due to wear, and if it is 200 .mu.m or more, the cost of plating increases, but on the other hand, there is no noticeable difference in effectiveness.

The particle size of silicon carbide powder in the composite plating layer is preferably 5 μm or less. This is because if the thickness exceeds 5 μm, the silicon carbide powder will not be sufficiently dispersed, impeding the uniformity of the plating layer and damaging the mating material it comes into contact with. However, it is desirable that the content (1) is 1.5 to 10% by weight. If it is less than 1.5% by weight, sufficient hardness and lubricity cannot be achieved, and if it is more than 10% by weight, it will not only reduce the conductivity of the plating layer but also cause problems such as making the plating layer brittle. It is.

The conductive hard particles are not limited to the silicon carbide powder mentioned above, but also fine particles such as carbides such as titanium carbide and tungsten carbide, nitrides such as titanium nitride and zirconium nitride, and borides such as zircon boride can be used. It is possible.

In the electric motor configured as described above, the composite plating layer 1a formed on the contact surface of the commutator 1 with the brushes 2 does not easily react with sulfur and chlorine in gasoline, so it does not generate sulfides or chlorides. The contact resistance of the contact surfaces is maintained low. In addition, the hardness of the plating layer is 500 to 500 on the Tockers hardness (Hv).
600, which is higher in hardness than copper-based materials (Hv 60 to 120), and therefore has excellent wear resistance against high hardness fine particles mixed in KARIN. As a result, the surface roughness of the commutator 1 is maintained in a dense state, suppressing the occurrence of arcs and exhibiting high resistance to electrical wear. As a result of examining various thicknesses of the composite plating layer through practical tests, good results were obtained when the thickness was 5 to 50 μm. In other words, if it is less than 5 μm, there is a risk that the composite plating layer will be worn out during long-term harsh specifications, and if it is more than 50 μm, the wear resistance will improve depending on the thickness, or if it is thicker than that, it is not suitable for backward use. Not particularly necessary, economically 5
It was advantageous up to about 0 μm.

Furthermore, the plating layer has high corrosion resistance against moisture in the fuel, and in order to maintain a stable surface condition, contact resistance is maintained low, and stable contact and sliding condition with the brush is maintained.

[Effects of the Invention As described above, the fuel pump electric motor according to the present invention has the following effects:
A composite plating layer containing nickel phosphorus and conductive hard particles is formed on the contact surface of the commutator with the brushes, which prevents deterioration due to corrosion and wear of the commutator and greatly improves its durability. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing a commutator of a conventional electric motor. In the figure, 1 is a commutator, 2 is a brush, and 1a is a composite plating layer. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) The weight ratio of the commutator contact surface with the brush is 90:
10 to 94:6 nickel and phosphorus with a particle size of 5μ
1. An electric motor for a fuel pump, comprising a composite plating layer having a thickness of 1 to 200 μm and containing conductive hard fine particles having a content of 1.5 to 10% by weight.